Brush



` sept. 25, 1934. c; CAHEN ET AL 1,974,795

BRUSH Original Filed Dec. 16. 1931 Patented Sept. 25, 1934 UNITED STATESPATENT OFFICE Renewed May 7, 1934.

3 Claims.

The present invention relates to the manufacture of brushes both largeand small, and to the resulting manufactured products. It particularlyconcerns an arrangement which permits maintaining the hairs or bristlesfirmly assembled in a bunch or tuft.

In the known arrangements, -the hairs are maintained by a sheet metalpiece or ferrule, by which they are surrounded over a considerablelength. The length of the hairs thus surrounded cannot be used, forminga drawback, since the commercial value or price of the brushes depends,as is well known, upon the effective length of the hairs or bristles.The present invention permits firmly assembling the hairs by contactover only a small part of their length, and thus the effective length ofthe hairs is greater than when the known methods of manufacture areused.

I-Iitherto, the assembly was made by winding around the set of hairs asheet metal band which was tightly pressed against the hairs, and as theband had a certain width, the hairs were retained by friction. On thecontrary, according to our invention, the hairs are mounted in a ring insuch manner that the butt ends of the hairs are all contained in thesaid ring or are near the same. It is a known fact that a hair orbristle has a tapered shape, thus having a top or small end and a bottomor butt end. Our new ring has but a small height, and thus it would beinsufficient to retain the hairs by friction, and for this reason, rodsof large diameter are driven into the ring, these being in the sameplane and perpendicular to the axis of the bunch of bristles. Thediameter of the rods is such that when they are inserted, they willreduce by at least 15 per cent the surface of the cross section of thebunch in the interior of the ring; and preferably, the section isreduced by 25 per cent. The space between any two rods and the innerwall of the ring thus forms a recess in which the bristles are firmlypressed and from which they cannot escape, owing to their tapered form.

It has already been proposed to: drive small nails into a bunch ofbristles, and such nails serve only to secure the bunch of bristles tothe wood handle. The diameter of these nails and their number in a givenplane are, however, insufficient to reduce the surface of the bristlesin this plane by 15 per cent; thus the bristles are not maintained inplace, and in order to hold them it is necessary to employ a ring orferrule of considerable height in order to hold the bristles byfriction, or else a tapered ferrule must be used,

In Germany December whose smallest cross section is distant from the "rplane vof the nails. In another arrangement, nails of small diameterhave been used in order to give the ferrule a shape different from thatof a ring, for instance in the flat brushes; and herein the nails extendclear through the ferrule and are riveted at their ends in such manneras to maintain the proper spacing between the opposite walls of theferrule. This arrangement is not as satisfactory as the present, as inthe known 55 construction the diameter and number of the nails areinsufficient to produce the desired effect, while on the other hand thesheet metal of the ferrule is very thin, and is not sufficiently rigidto withstand the high pressures produced in the 7.0 present arrangement.

The ring preferably has a circular shape, as this will prevent alldistortions due to high pressure.

It is advantageous to give the ring the form of a truncated cone whosesmall base is quite close g5 to the plane of the rods, and thus the ringwill add its effect to that of the rods.

In the accompanying drawing:

Figure 1 is a section on the axis of a bunch of bristles, according tothe invention. Figure 2 is a horizontal section on the line II-II ofFigure 1.

For the manufacture of the set of bristles shown in Figures 1 and 2, thebristles 1 are first assembled in such manner that all the small endsare at the top, the butt ends being at the bottom at 3. The bottom partof the bunch is then inserted into a ring 4 having the shape of atruncated cone. The ring consists of copper, and has a diameter of 34mm. and a thickness of 1 mm.; 90 so that it will be strong enough toresist all distortion. Holes are pierced in the ring 4 near itsnarrowest part 6; the wedging rods 5 are inserted through the said holesand have the radial position, all the rods being situated in the sameplane. The rods have a circular cross section and are 2 mm. in diameter.

In this manner the bristles are distributed among the spaces which areformed in each case by a part of the wall of the ring 4 and of any 100two adjacent rods 5; in each space, the cross secf tion available forthe bristles increases when approaching the butt ends of the bristles,and thus the latter are wedged into place.

On the other hand, they are rmly held in .105 place, as the crosssection available for the bristles before inserting the rods, that is,the surface within the ring and adjacentv the rods, is 910 sq. mm.; thetotal surface covered by the rods in the common plane passing throughtheir axes is ,110

192 sq. mm.; or 21 per cent of the surface of the rod, and thus afterinserting the rods, the surface left for the bristles is only '718 sq.mm. Hence the reduction of the cross section is 21 per cent. To thismust be added the tightening action due to the narrowest part 6 of thering. It will be noted that a very small part of the length of thebristles is made ineffective by the ring 4; this part is equal to theheight of the ring, or about '7 sq. mm.

Obviously, the ring 4 may consist of a sheet metal strip or of a WireWinding, without departing from the principle of the invention or themethod of manufacture.

What We claim is:

1. A bunch of bristles comprising a tapering ring enclosing the buttends of the bristles, and nails of large diameter extending through thering and part Way across the bristles, the said nails extendingperpendicularly to the major axis of the bunch of bristles and being allsituated in substantially the same plane, perpendicular to the saidaxis.

2. A bunch of bristles according to claim 1 in which the plane of thesaid nails is closely adjacent to the small base of the tapering ring.

3. A bunch of bristles following claim 1, in which the rods have adiameter such that the total surface occupied by the rods in the planecommon to their axes, represents more than a sixth of the total surfaceof the circular area of the ring in the said plane.

GEORGES CAI-IEN. PAUL CHEVALIER.

